This invention relates to surface analysis techniques, and more particularly to dynamic reference plane leveling.
Numerous technical applications involve measuring aspects of a surface. For example, in the disk drive industry, determining the microscopic topology of a disk surface at various stages during production is becoming an increasingly important factor in estimating the likelihood of producing a favorable quality disk. Given the very high density of data stored on such disks, topographic profiles with heights ranging from less than one nm to tens of microns are monitored at a lateral resolution on the order of one micron.
In some storage devices such as hard disk drives, a read/write head is disposed closely adjacent a rotating disk. The read/write head enables magnetic (rather than physical) access to the disk to read and/or write bits of data. However, if the read/write head touches the disk surface, the data that is magnetically stored on the disk may be damaged. Also, damage to the head may occur if the head physically contacts the rotating disk. In some current hard disk drives, extensive damage may be caused to both the head and the rotating disk surface if they physically come in contact, since the disks can spin at speeds of several thousands of revolutions per minute (RPM).
To store as much data as possible in a given footprint of a hard disk drive, the heads are kept at increasingly shorter distances from the rotating disks. Hence, accurate measurement of the distance between the head and the rotating disk is useful.